MAPT and argyrophilic grain disease: Tau pathology is a defining characteristic of a number of human neurodegenerative diseases, including Alzheimer's disease, progressive supranuclear palsy, corticobasal degeneration, argyrophilic grain disease, chronic traumatic encephalopathy and some cases of frontotemporal dementia.1, 2 Physiologically, tau promotes microtubule assembly and stability.